package com.hmdp.service.impl;

import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSON;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisConstants;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import org.springframework.data.geo.Circle;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.Resource;
import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;


    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        if (x==null||y==null) {
            // 根据类型分页查询
            Page<Shop> page = query()
                    .eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        int from = (current-1) * SystemConstants.DEFAULT_PAGE_SIZE;
        int end = current * SystemConstants.DEFAULT_PAGE_SIZE;
        GeoResults<RedisGeoCommands.GeoLocation<String>> search = stringRedisTemplate.opsForGeo().search(
                RedisConstants.SHOP_GEO_KEY + typeId,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeDistance().limit(end));

        if (search == null) {
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> content = search.getContent();
        if (content.size()<=from) {
            return Result.ok(Collections.emptyList());

        }
        List<Long> ids = new ArrayList<>(content.size());
        Map<String,Distance> distanceMap = new HashMap<>();
        content.stream().skip(from).forEach(result->{
            String id = result.getContent().getName();
            ids.add(Long.valueOf(id));
            Distance distance = result.getDistance();
            distanceMap.put(id,distance);
        });
        String idsStr = StrUtil.join(",", ids);
        List<Shop> list = query().in("id", ids).last("ORDER BY FIELD(id," + idsStr + ")").list();
        for (Shop shop : list) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        return Result.ok(list);
        // 返回数据


    }

    @Override
    public Result queryById(Long id) {
        //缓存穿透
//        Shop shop = queryWithPassThrough(id);
        //互斥锁解决缓存击穿
        Shop shop = queryWithMutex(id);
        //逻辑过期实现缓存击穿
//        Shop shop = queryWithExpireTime(id);
        if (shop == null) {
            return Result.fail("店铺不存在");
        }
        return Result.ok(shop);
    }

    public Shop queryWithPassThrough(Long id){
        String shopJSON = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY + id);
        if (StrUtil.isNotBlank(shopJSON)) {
            return JSONUtil.toBean(shopJSON, Shop.class);
        }
        if (shopJSON != null) {
            return null;
        }
        Shop shop = getById(id);
        if (shop == null) {
            stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,"",RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
            return null;
        }
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(shop),RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        return shop;
    }

    private static final ExecutorService CACHE_REBUILD_EXECUTOR = Executors.newFixedThreadPool(10);
    public Shop queryWithExpireTime(Long id){
        String shopJSON = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY + id);
        if (StrUtil.isBlank(shopJSON)) {
            return null;
        }
        RedisData bean = JSONUtil.toBean(shopJSON, RedisData.class);
        Shop shop = JSONUtil.toBean((JSONObject) bean.getData(), Shop.class);
        if(bean.getExpireTime().isAfter(LocalDateTime.now())){
            return shop;
        }
        boolean tryLock = tryLock(RedisConstants.LOCK_SHOP_KEY + id);
        if (tryLock) {
            CACHE_REBUILD_EXECUTOR.submit(() ->{
                try {
                    saveShop2Redis(id,20L);
                }catch (Exception e){
                    e.printStackTrace();
                }finally {
                    unlock(RedisConstants.LOCK_SHOP_KEY+id);
                }
            });
        }
        return shop;
    }

    public Shop queryWithMutex(Long id){

        String shopJSON = stringRedisTemplate.opsForValue().get(RedisConstants.CACHE_SHOP_KEY + id);
        if (StrUtil.isNotBlank(shopJSON)) {
            return JSONUtil.toBean(shopJSON, Shop.class);
        }
        if (shopJSON != null) {
            return null;
        }
        Shop shop = null;
        try {
            boolean tryLock = tryLock(RedisConstants.LOCK_SHOP_KEY + id);
            if (!tryLock) {
                Thread.sleep(50);
                return queryWithMutex(id);
            }
            shop = getById(id);
            if (shop == null) {
                stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY + id, "", RedisConstants.CACHE_NULL_TTL, TimeUnit.MINUTES);
                return null;
            }
            stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY + id, JSONUtil.toJsonStr(shop), RedisConstants.CACHE_SHOP_TTL, TimeUnit.MINUTES);
        }catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unlock(RedisConstants.LOCK_SHOP_KEY + id);
        }
        return shop;
    }

    private void saveShop2Redis(Long id,Long expireSeconds){
        RedisData redisData = new RedisData();
        redisData.setData(getById(id));
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireSeconds));
        stringRedisTemplate.opsForValue().set(RedisConstants.CACHE_SHOP_KEY+id, JSONUtil.toJsonStr(redisData));
    }

    private boolean tryLock(String key){
        //避免自动拆箱
        return BooleanUtil.isTrue(stringRedisTemplate.opsForValue().setIfAbsent(key,"1",RedisConstants.LOCK_SHOP_TTL,TimeUnit.SECONDS));

    }

    private void unlock(String key){
        stringRedisTemplate.delete(key);
    }

    @Override
    @Transactional
    public Result update(Shop shop) {
        Long id = shop.getId();
        if (id == null) {        //为什么会是null
            return Result.fail("店铺的id不能为空");
        }
        updateById(shop);

        stringRedisTemplate.delete(RedisConstants.CACHE_SHOP_KEY+id);

        return Result.ok();
    }
}
